The present invention relates to a refrigeration system which includes structure for unloading its compressor while permitting it to continue in operation by passing hot gas from its outlet to its inlet in various ways.
In the past, there were various ways of unloading a hermetic compressor when refrigeration was not required, and such methods included cycling the compressor on and off and by bypassing compressor discharge refrigerant directly into the suction line. Thus hermetic compressors were controlled in the past either by cycling the compressor on and off in response to demand or providing an artificial load with a discharge bypass valve equal to the difference between the real load and the systems capacity. Other methods included the use of pressure regulators and liquid or suction line solenoid valves controlled with thermostats. However, the various prior systems were undesirable in that they either constituted a waste of power or did not provide precise control or they involved the risk of oil starvation to the compressor.